The computer is a purpose device that can be programed to carry out a finite set of arithmetic or logical operations. Computer can solve more than one kind of problems. Charles babbage was the one who created computers. Overview

The first generation of computers is said by some to have started in 1946 with ENIAC. the first 'computer' to use electronic valves (ie. vacuum tubes). In 1946 there was no 'best' way of storing instructions and data in a computer memory.

During the period of 1956 to 1963 second generation of computers were developed. The second generation computers emerged with development of Transistors. The transistor was invented in 1947 by three scientists J. Bardeen, H.W. Brattain and W. Shockley. A transistor is a small device made up of semiconductor material like germanium and silicon. Even though the Transistor were developed in 1947 but was not widely used until the end of 50s. The transistor made the second generation computers faster, smaller, cheaper, more energy-efficient and more reliable than their first-generation computers.

The third generation of computing was characterized by the transition from transistors to the integrated circuit chip (invented in 1958 by Jack Kilby of Texas Instruments, and Robert Noyce of Fairchild Semiconductor Corp.). The basic idea behind the IC chip was to build a complete electronic circuit into a single block of material, eliminating the tangled mess of wiring needed to connect individual transistors, resistors, capacitors, etc. This became known as "solid- state" technology. Magnetic core memory continued to be the standard memory technology throughout the 1960s. Although magnetic cores were becoming smaller, the physical size and dimensions of a magnetic core "stack" limited practical memory capacity to between 64 KB and 256 KB

After 1971 the fourth generation computers were built. The fourth generation computers were the extension of third generation technology. The fourth generation computers emerged with development of the VLSI (Very Large Scale Integration).With the help of VLSI technology microprocessor came into existence The computers were designed by using microprocessor, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The fourth generation computers became more powerful, compact, reliable and affordable. As a result, they give rise to personal computer (PC) revolution.

Computer hardware refers to the physical components of the computer such as, monitor, keyboard, hard disk, mouse, etc. Refers to objects that you can actually touch like, disk, disk driver, display screen, keyboard, printer, boards and chips. Computer hardware is the collection of physical elements that comprise a computer.

Hardware= Modern computer hardware (the physical components of the computer) has come a long way in just over a half century. Yet many of the principal concepts and technology behind this hardware remain essentially the same. For example, as mentioned previously, Babbage's work on the Analytical Engine in the early 1800s defined several a the major subsystems of modern computers: input, memory, processing, and output Input= Input device allow an individual to enter information so that the computer can do the work it is designed to do. Output= Without output device we have no idea that computer is doing the right thing. In fact, we would not really know if it was working at all.

Central processing unit (CPU), an electronic circuit which executes computer programs, containing a processing unit and a control unit. Microprocessor, a CPU on one silicon chip as part of a microcomputer. Graphics processing unit (GPU / VPU), a dedicated graphics rendering device for a personal computer or game console. Physics processing unit (PPU), a dedicated microprocessor designed to handle the calculations of physics

A hard disk drive ( HDD ; also hard drive, hard disk, or disk drive ) is a device for storing and retrieving digital information, primarily computer data. It consists of one or more rigid (hence "hard") rapidly rotating discs (platters) coated with magnetic material, and with magnetic heads arranged to write data to the surfaces and read it from them. Removable storage, in computing terms, is any form of data storage which is not incorporated into the computer itself. It takes many forms, running the gamut from primitive punch cards to memory sticks, and the capacity varies widely depending on the type of removable storage and how old it is.

A computer network, or simply a network, is a collection of computers and other hardware components interconnected by communication channels that allow sharing of resources and information. Where at least one process in one device is able to send/receive data to/from at least one process residing in a remote device, then the two devices are said to be in a network. Simply, more than one computer interconnected through a communication medium for information interchange is called a computer network.

An operating system ( OS ) is a collection of software that manages computer hardware resources and provides common services for computer programs. The operating system is a vital component of the system software in a computer system. Application programs require an operating system to function. Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting for cost allocation of processor time, mass storage, printing, and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware.

Application software, also known as an application or an app, is computer software designed to help the user to perform specific tasks. Many application programs deal principally with documents. Apps may be bundled with the computer and its system software, or may be published separately. Some users are satisfied with the bundled apps and need never install one.